501. Surveys of Petersham Lots Creator: Gould, E. M. Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: 1976–1978 Institution: Harvard Forest Archives
502. SW00 0 x 0 ft. Block of Lyford Grid Creator: Lyford, Walter Henry, 1909-, Carolan, Peter, and Kretschmar, Holly Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 3, 1969–June 2, 1992 Institution: Harvard Forest Archives
503. SW01 0 x 100 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Hoagland, Ralph P., Carlson, Joel, Yao, Peikang, and Jacobson, Tom Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: February 23, 1969–June 2, 1992 Institution: Harvard Forest Archives
504. SW10 100 x 0 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 1, 1969–June 28, 1991 Institution: Harvard Forest Archives
505. SW11 100 x 100 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 4, 1969–July 8, 1991 Institution: Harvard Forest Archives
506. SW20 200 x 0 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 3, 1969–July 25, 1991 Institution: Harvard Forest Archives
507. SW21 200 x 100 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Kretschmar, Holly, and Carolan, Peter Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: April 30, 1969–June 8, 1992 Institution: Harvard Forest Archives
508. SW22 200 x 200 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 1, 1969–July 18, 1991 Institution: Harvard Forest Archives
509. SW30 300 x 0 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: April 30, 1969–July 26, 1991 Institution: Harvard Forest Archives
510. SW31 100 x 300 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Williams, Wesley C., Gemborys, S. R., Carolan, Peter, and Kretschmar, Holly Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: August 9, 1962–May 10, 1992 Institution: Harvard Forest Archives
511. SW32 200 x 300 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Sperry, Steve, Gemborys, S. R., Carolan, Peter, and Kretschmar, Holly Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: August 9, 1962–May 12, 1992 Institution: Harvard Forest Archives
512. SW33 300 x 300 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Williams, Wesley C., Gemborys, S. R., Carolan, Peter, and Kretschmar, Holly Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: April 21, 1969–May 15, 1992 Institution: Harvard Forest Archives
513. SW34 300 x 400 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Carolan, Peter, and Kretschmar, Holly Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 8, 1969–May 17, 1992 Institution: Harvard Forest Archives
514. SW40 400 x 0 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Keith, Kasey Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: April 30, 1969–July 25, 1991 Institution: Harvard Forest Archives
515. SW41 100 x 400 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Gemborys, S. R., Kretschmar, Holly, and Carolan, Peter Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: August 8, 1962–June 30, 1992 Institution: Harvard Forest Archives
516. SW42 400 x 200 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Williams, Wesley C., Gemborys, S. R., Kretschmar, Holly, and Carolan, Peter Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: August 8, 1962–June 7, 1992 Institution: Harvard Forest Archives
517. SW43 400 x 300 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Sperry, Steve, Gemborys, S. R., Kretschmar, Holly, and Carolan, Peter Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: August 9, 1962–June 22, 1992 Institution: Harvard Forest Archives
518. SW44 400 x 400 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-, Kretschmar, Holly, and Carolan, Peter Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 8, 1969–June 23, 1992 Institution: Harvard Forest Archives
519. SW50 500 x 0 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909-; Micks, P. Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 2, 1969–August 15, 1991 Institution: Harvard Forest Archives
520. SW51 500 x 100 ft. Block Lyford Grid Creator: Lyford, Walter Henry, 1909- Format: Maps/Atlases Collection: The Harvard Forest Map Collection Date: May 15, 1969–August 21, 1991 Institution: Harvard Forest Archives